This invention relates in general to printing, and more particularly to an appliance that facilitates handling the unprinted ribbons during the start up procedure for a press.
In high speed printing of the type used for high quality magazines, two webs, which are merely extended lengths of paper, pass through press units where printed impressions are applied, usually by lithographic techniques, to both surfaces of the webs. In color printing, each press unit applies a different color, and to obtain full color four press units are normally required--one for each of the three primary colors and another for black. Thus, a press which prints in full color on two webs will normally have eight press units. Each web is considerably wider than a magazine page and as a consequence several pages are printed side-by-side on a web. Indeed, the normal practice is to print four pages across on each surface of a web.
Immediately beyond the press units, the webs pass into a dryer where solvents are evaporated from the ink, leaving a permanent printed impression on the web. After the dryer each web passes through a slitting apparatus where it is slit midway between its side margins into two ribbons, each having two rows of pages arranged side-by-side in it. These ribbons then pass through a turning device comprising turning bars and multiple rollers, and here the ribbons are directed laterally with respect to the web travel line. The ribbons emerge from the turning device with one overlying the other and further such that the pages on one will subsequently align or register with the pages on the other.
The overlying ribbons thereafter pass through a folder containing a forming board and two rolls at the bottom of each forming board. Here the ribbons from each web are folded in half and over onto each other such that one folded ribbon of the web lies within the other ribbon of the web. Indeed, at the forming board, the ribbons from both of the webs may be brought together so that four folded ribbons emerge one within the other.
Next the folded ribbons pass through a cutter which is part of the folder, and here the ribbons are severed transversely between successive pages. The result is a succession of signatures, which are suitable for later assembly with other signatures into a book or magazine. In any event, the final component of the press is a stacker which arranges the signatures one upon the other, so they may be lifted as bundles from the press and transported to a binding machine for assembly into a magzine or book.
It is not uncommon for high speed printing presses to operate with the webs and ribbons moving at between 1000 and 1400 ft./ min., but before a press can be set in operation at this speed, the webs must be fed through the several printing units and the drier and thereafter threaded through the slitter and turning device. This is done with the press operating at a much slower speed known as the "walk speed". Moreover, during start up, adjustments are sometimes made at the various components to insure that colors are correct, that pages register, and that cuts will be made at the proper locations, and the "walk speed" provides an opportunity to make such adjustments, or at least check them.
The cutter, which is immediately beyond the forming board of the folder does not cut properly at walk speed, and accordingly, it is common practice in the operation of presses to withdraw the ribbons from the press before they reach the forming board. The ribbons at this point are directed laterally. Usually a pressman stands at the side of the press winding the waste ribbons by hand, so that they do not accumulate on the floor to the side of the press where they might interfere with the work of other pressman or become entangled in the stacker. When the press speed is increased, the pressman quickly tears the ribbons and feeds them over the forming board and in between the folding rolls at the bottom of that board. The ribbons then continue to the cutter where they are cut into signatures which emerge in a stack from the stacker.
A pressman's services are mostly needed during the time when a press operates at walk speed, and to use a pressman at this time to merely control and dispose of the waste ribbons is indeed wasteful.